1. Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical Engineering Tsinghua University Beijing 100084 P. R. China
2. Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of Education School of Physics and Electronic Engineering Harbin Normal University Harbin 150025 P. R. China
3. School of Mining and Petroleum Engineering Department of Civil and Environmental Engineering University of Alberta Edmonton ABT6G 1H9 Canada
4. Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing 100081 P. R. China